G = { V, E } V = { i | 0 ≤ i < n } E = { (u,v) | u,v ∈ V and v = 2u+1 or v = 2u+2 } For all u ∈ V, there is a numeric value val(u). If (u,v) ∈ E, then val(u) ≤ val(v).